WCD-Style Belly Pan Weight

After cadding up a 1/8" 6061 “WCD-style” belly pan, Inventor calculated its weight to be around 5.2 lbs. **Would anybody consider this to be an accurate measurement? ** Assuming it has a diamond/cross hatch pattern similar to the ones displayed in this thread and encompasses the entire bottom part of the drive base.

Strictly in terms of weight, 5.2 lbs is around a pound lighter than the 1/4" unpocketed polycarbonate sheet that we used this year and had no problems with.

Sounds reasonably correct. My team used a 1/16" belly pan (5052 aluminum) this year with no pocketing and it weighed 5 pounds. Assuming you’re using something like 6061, 6063, 5052 depending on the size and how much pocketing, 5.2lbs is reasonable for all of those.

What our team has used for the last few years is a type of plastic extrusion called veralite it’s really light, but if you mount it so that the grain of the plastic cells is right for the load, it can be way more rigid than polycarbonate sheets. for example, out bellypan this year for our WCD was about .3 pounds. it’s also easy to drill holes in for zipties and other wire routing hardware.

We did 1/8" 5052 on a prototype with a ton of pocketing, and it came to 4.5lbs or 5lbs. One of our main reasons for the bellypan is keeping the frame stiffer in torsion. Have you found any advantages to 1/16", especially if the weight is about the same as pocketed 1/8"?

Also, remember that a belly pan the one of the closest things to the ground on any robot. This helps lower you CG, which is really important in most games, and very important on any 6 wd bot. Furthermore, with lightening, it allows you secure attachment of electronics, and stiffens the whole frame. Therefor, it is worth the weight to invest in a bellypan.

i havent seen a west coast drive bot with this but i’d think polygal would work a bottom pan.

Our belly pan this year on our 2012 robot is ~2.5 lbs. We could’ve made it a little lighter. We added/left material where we thought we would need it for mounts/stingers in the feature.


What material is it?

Fairly positive its just 1/8" 6061.

Aluminum - 6061 - 1/8" Thick


We went with wood after our aluminum bellypan (much like the one shown above) turned out to be about 5 pounds, which put us overweight. The wood performed great and was much lighter than the metal after we gave a freshman a two inch hole saw. In the end it weighed between 2-3 pounds.

This has come up many times in the past and I always respond with make a composite belly pan. From a mentors view making the belly pan - electronics board from composites is an excellent way to introduce students to the mystical world of composite construction. What our team does is take a 1/4 " , 4mm or 6mm piece of birch ply wood and laminate both sides with 5.7 OZ plain weave carbon fiber using vacuum bagging methods. It’s not that hard and is doable by most teams. 11 of our student got hands on experience this year. All though keeping the students focused and neat, not making a gooey mess can be quite mentally draining. The end product is a wonderful material. I can provide some link if needed or search youtube, there are some good videos on it.

We use 1/16 primarily because that’s what our metal shop has standard in stock. So it’s cheaper (actually free) for us to use 1/16, and the turnaround time is faster. We also typically put a few flanges on the sides to make the pan sit nicely in the frame with lateral support.

But you’re right, 1/8 acts to stiffen the frame much more than 1/16 does, for us it’s just a matter of what resources are most readily available.

Wow, our cheesing patterns must be very different then…

When you get a chance, send me a solidworks file.

I’ll take a look at it for ya!


Hi R.C.,

Would you mind posting a CAD of 1323’s belly pan? I would love to see how we could improve ours! 2.5 pounds is amazingly light.

Sure will do,

I’ll post sometime tomorrow when I get to the shop.


Sorry for the double post,

I was a little off, its more ~2.75, we added a few things late :stuck_out_tongue:

Attached Step File.

drivetrain_bellypan.zip (824 KB)


drivetrain_bellypan.zip (824 KB)

drivetrain_bellypan.zip (824 KB)